Dahlia (Dahlia pinnata L.) is one of the most popular and attractive cut flower plants around the world. Many fungi like Sclerotium rolfsii, Fusarium solani and Macrophomina phaseoli and bacteria like Erwinia carotovora pv. carotovora, E. carotovora pv. chrysanthemi, Pseudomonas cichorii and Bacillus polymyxa are attacking dahlia plants in the field, storage and during propagation by stem or divided cuttings.